Print head and manufacturing method thereof

Abstract

A print head includes an orifice plate having a plurality of orifices arranged as ink-jet nozzles, and a head body partitioned into a plurality of ink chambers and integrated with the orifice plate such that ink is guided from the ink chambers to the orifices, for increasing an internal pressure of each ink chamber to eject ink from a corresponding orifice. Particularly, each orifice has a constriction for restricting an ink-jet error angle to a range of ±5 mrad with respect to a center axis thereof.

What is claimed is:  
     
       1. A print head comprising: 
       an orifice plate having a plurality of orifices arranged as ink-jet nozzles; and  
       a head body which is partitioned into a plurality of ink chambers and integrated with said orifice plate to guide ink from the ink chambers to the orifices;  
       wherein said head body increases an internal pressure of each ink chamber to eject ink from a corresponding orifice; and  
       wherein each orifice comprises forward and reverse tapers forming a constriction which is symmetric with respect to a center axis of the orifice; and  
       wherein said forward and reverse tapers have a boundary which serves as a narrowest part of the constriction.  
     
     
       2. A print head comprising: 
       an orifice plate having a plurality of orifices arranged as ink-jet nozzles; and  
       a head body which is partitioned into a plurality of ink chambers and integrated with said orifice plate to guide ink from the ink chambers to the orifices;  
       wherein said head body increases an internal pressure of each ink chamber to eject ink from a corresponding orifice;  
       wherein each orifice comprises forward and reverse tapers forming a constriction which is symmetric with respect to a center axis of the orifice; and  
       wherein an aperture size of said forward taper gradually decreases to a predetermined value in a thickness direction of said orifice plate from an ink supply side to an ink discharge side.  
     
     
       3. A print head according to  claim 2 , wherein said constriction restricts a direction of ink ejection to within an angle of ±5 mrad with respect to the center axis of the orifice. 
     
     
       4. A print head according to  claim 2 , wherein an aperture size of said reverse taper gradually increases from the predetermined value in the thickness direction of said orifice plate from the ink supply side to the ink discharge side. 
     
     
       5. A print head according to  claim 2 , wherein a depth of said reverse taper is not greater than 30% of a thickness of said orifice plate. 
     
     
       6. A print head according to  claim 2 , wherein a depth of said reverse taper is not greater than 20% of a thickness of said orifice plate. 
     
     
       7. A print head according to  claim 2 , wherein said orifice plate includes a liquid-repellent film formed as a surface on the ink discharge side and surrounding said reverse taper. 
     
     
       8. A print head manufacturing method comprising: 
       bonding an orifice plate to a head body which is partitioned into a plurality of ink chambers,  
       irradiating said orifice plate with a laser beam to form a plurality of orifices which are arranged as ink-jet nozzles communicating with the ink chambers to eject ink in response to an increase in internal pressure of the ink chambers;  
       wherein each orifice is shaped by converging the laser beam using an imaging optical system whose focal plane is set inside said orifice plate so as to simultaneously form in each orifice a forward taper whose aperture size gradually decreases to a predetermined value in a thickness direction of the orifice plate from an ink supply side to an ink discharge side, and a reverse taper communicating with the forward taper.  
     
     
       9. A method according to  claim 8 , wherein said orifices are formed and shaped after said orifice plate is bonded to said head body. 
     
     
       10. A method according to  claim 8 , wherein said laser beam is irradiated onto a surface of said orifice plate on an ink discharge side. 
     
     
       11. A method according to  claim 10 , wherein said orifice plate includes a liquid-repellent film serving as the surface of said orifice plate onto which the laser beam is irradiated. 
     
     
       12. A method according to  claim 11 , wherein said orifices are shaped by irradiating the laser beam onto said liquid-repellent film in a state where said liquid-repellent film is adhesively covered with a protective film, and then removing said protective film after irradiation of the laser beam. 
     
     
       13. A method according to  claim 8 , wherein a depth of said reverse taper is determined by a position of the focal plane of said imaging optical system shifted in the thickness direction of said orifice plate. 
     
     
       14. A method according to  claim 8 , wherein an aperture size of said reverse taper gradually increases from the predetermined value in the thickness direction of said orifice plate from the ink supply side to the ink discharge side. 
     
     
       15. A method according to  claim 8 , wherein a depth of said reverse taper is not greater than 30% of a thickness of said orifice plate. 
     
     
       16. A method according to  claim 8 , wherein a depth of said reverse taper is not greater than 20% of a thickness of said orifice plate. 
     
     
       17. An orifice plate comprising: 
       a lamination member comprising a resin plate and a liquid-repellent film covering the resin plate;  
       a plurality of orifices arranged as ink-jet nozzles in said lamination member;  
       wherein each orifice comprises a constriction formed by a combination of a forward taper whose aperture size gradually decreases to a predetermined value in a thickness direction of said lamination member from an ink supply side to an ink discharge side, and a reverse taper communicating with the forward taper and having a depth not greater than 30% of a thickness of said lamination member.  
     
     
       18. An orifice plate according to  claim 17 , wherein the depth of said reverse taper is not greater than 20% of the thickness of said lamination member. 
     
     
       19. An orifice plate manufacturing method comprising: 
       forming a lamination member from a resin plate and a liquid-repellent film;  
       irradiating said lamination member with a laser beam to form a plurality of orifices arranged as ink-jet nozzles in said lamination member;  
       wherein each orifice is shaped by converging the laser beam using an imaging optical system whose focal plane is set inside said lamination member so as to simultaneously form in each orifice a forward taper whose aperture size gradually decreases to a predetermined value in a thickness direction of the lamination member from an ink supply side to an ink discharge side, and a reverse taper communicating with the forward taper and having a depth not greater than 30% of a thickness of said lamination member.  
     
     
       20. A method according to  claim 19 , wherein the depth of said taper is not greater than 20% of the thickness of said lamination member.